Flex lift apparatus and method



D. A. FOGG 3,366,410

FLEX LIFT APPARATUS AND METHOD 2 Sheets-Sheet 1 INVENTOR. fid/U/Ei 4.[4&6

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Jan. 30, 1968 Filed Oct. 21, 1965 BY ATTORNEYS D. A. FOGG Jan. 30, 1968FLEX LIFT APPARATUS AND METHOD 2 Sheets-Sheet 2 Filed Oct.

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ATTORNEYS United States Patent 3,366,410 FLEX LIFT APPARATUS AND METHODDaniel A. Fogg, White Cloud, Mich., assiguor to The Rapids-StandardCompany, Inc., Grand Rapids, Mich., a corporation of Michigan Filed Oct.21, 1965, Ser. No. 499,521 8 Claims. (Cl. 294-64) ABSTRACT OF THEDISCLOSURE Apparatus and method for hoisting patterns of articles suchas filled cartons, having a lifting platen closing one face of a plenumchamber with which evacuation means is communicant, the platen havinglimited air flow orifices therethrough, being retained from stretching,but being slightly flexible to bend, in response to a pressuredifferential thereacross, to a compound curvature matching the peripheryof the pattern of articles in a manner to seal the periphery whileforming a communicant space within this periphery between articles andthe platten.

This invention relates to article hoist equipment, and more particularlyto pressure differential hoisting apparatus.

The hoisting apparatus illustrated and disclosed herein was developedprimarily for hoisting groups of cartons arranged in patterns, e.g.square or rectangular, and transferring them from one location toanother. For convenience, the apparatus will be described largely withrespect to this type of article. It will be realized however, uponstudying the disclosure, and understanding the concept taught, that manytypes of articles could conceivably be hoisted with the apparatus.

Various types of pressure differential hoisting apparatuses have beendeveloped heretofore using a negative pressure plenum chamber, and anopen mesh article engaging lifting platen to contact the upper surfacesof a group of cartons in a pattern. These have been used, for example,in the palletizing field, to transfer groups of cartons on to or olf ofpallets, loading platforms, etc. With the usual pressure differentialhoisting units, it is important to have a good seal between the liftingunit and the outside of the outermost carton in a pattern to minimizeair leakage and maintain a sufficient pressure differential for safe,reliable hoisting. Yet, since groups of cartons to be lifted contain aplurality of individual cartons, it is not aways possible or likely toobtain a good seal with all of the cartons and without leakage bebetweenthe cartons. Hence, peripheral depending curtains, peripheral resilientcushions, and gap filling cushions have been employed on the bottom offiat lifting platens to improve the likelihood of obtaining a good sealaround and between the cartons. These supplemental devices, whileimproving sealing probabilities, immediately cause limitations in thesize and configurations of the carton patterns to be hoisted with aparticular hoist, since the suspending devices must match the cartonpattern dimensions and configuration to extend closely around theperiphery of the pattern. If these elements are not closely adjacent theouter faces or edges of the cartons, a complete seal is not obtained andthe pressure diflferential is largely destroyed. This factor limits theutility of any. particular hoist therefor. It also causes a slowdown inthe rate of hoisting operations due to the necessity for exact alignmentof the hoist with each pattern of cartons. If different carton patternsare to be hoisted, each hoist unit must be specifically modified toaccommodate that particular pattern configuration and/ or size.

Another critical operational factor involved with pressure differentialor vacuum hoist units is the necessity of obtaining good air flowcomunication from the suction ports in the platen over the completeupper surface area of the group of cartons, including the outermostcartons, but without allowing communication from just beyond theoutermost cartons to the suction apparatus, since the resultant leakagelargely destroys the pressure dilferential needed to lift the cartons.Accordingly, it has been necessary to exactly control the area of thesuction ports with respect to the dimensions of the group of cartons bythe use of sliding doors, or the noted curtains and resilient cushions.It will be realized that the area of the suction ports must not only bethe same size as the carton area, but must coincide exactly with it whenaligned.

All of these considerations have caused known lifting units to be fairlycomplex in construction, relatively expensive, and specifically limitedin application to particular carton pattern sizes and configurations, aswell as having limited efficiency due to the time consumption necessaryto manipulate, align, and exactly position the hoist with respect toeach particular group of cartons.

It is an object of this invention to provide a novel hoist unit capableof employment on carton patterns of subtantialiy differing dimensionsand pattern configuration, yet without any supplemental curtains,cushions, slide doors and the like.

Another object of this invention is to provide a novel pressuredifferential hoist unit achieving excellent communication between theupper surfaces of all of the cartons in a group to the passages for theevacuation means, yet always with excellent sealing action between theouter peripheral edges on the outermost cartons and the lifting platen,even with carton pattern variations, to prevent significant leakage thatcould destroy the operative pressure differential.

Another object of this invention is to provide a pressure differentialhoisting apparatus that is actually relatively simple in construction,with no suspended supplemental peripheral members, yet capable ofrepeatedly automatically obtaining excellent sealing action on thesurfaces to be hoisted, and of maintaining suflicient pressuredifferential over the entire surface area, even though the size andconfiguration of the surface area varies from one hoisting action to thenext.

Another object of this invention is to provide a pressure differentialhoist apparatus having a unique platen flexing action that automaticallyaccommodates the hoist to the particular dimensions and configurationsof the surface area, e.g. of cartons to be hoisted, to cause optimumperipheral edge sealing of the surface area, and complete communicationto the entire surface area inside the peripheral edge, thereby obtaininga maximum pressure differential hoisting force.

These and several other related objects of this invention will becomeapparent upon studying the following specification in conjunction withthe drawings in which:

FIG. 1 is a perspective view of the top portion of the hoist unit;

FIG. 2 is a perspective view of the underside of the novel hoist unit,showing the orificed lifting platen;

FIG. 3 is a fragmentary perspective view of the valve operatingmechanism for the evacuation discharge, taken in the direction indicatedby the arrow III in FIG. 1;

FIG. 4 is a side elevational sectional view of the plenum chamber andlifting platen portion of the apparatus showing its relationship to agroup of cartons prior to evacuation;

FIG. 5 is a sectional view of the apparatus in FIG. 4, showing therelationship during evacuation and hoisting; and

FIG. 6 is a sectional view similar to the views in FIGS.

aseano 4 and 5 but showing a modified construction of the assembly.

Referring now specifically to the drawings, the complete assembly th reshown includes the housing 12 forming an internal plenum chamber, blowertype evacuation means 14- mounted on an operative housing 12, electricmotor 16 drivingly connected to evacuation means 14, and control means18 operatively associated with electrical switching and connectionsystem 29 to motor 16 and solenoid assembly 22 that controls exhaustvalve 24 of the blower.

Housing subassembly 12 includes an upper horizontal support platform 3ihaving a depending peripheral connection flange 3t). Mounted to flange3%) is a peripheral bracket flange 32 forming an opening over which aspecial underside panel 34 is secured as by bolts 36. The nature ofpanelG-iis important to this invention. It is perferably a metal sheethaving slight flexibility to bend from a generally flat configuration(as shown in FIG. 4), to a slightly inwardly curved, concave, compoundcurvature configuration with a large radius of curvature (as shown inH6. 5). Preferably, the member is nonstretchable so as not to drawuncontrollably into the housing under a pressure differential acrossit.' It is generally semi-rigid with only slight flexibility. Thespecific curvature illustrated in FIG. 5 is actually exaggerated forpurposes of illustration. The actual height difference between thecenter and edges of a panel on a hoist several feet wide and severalfeet long is only a small fraction of an inch.

The curvature is initially created by a pressure differential across thepanel in a manner to be described, and is maintained by a pressuredifferential across the combined cartons and panel as describedhereinafter. The curvature is controlled as by limiting it, for example,by a plurality of stop members such as adjustable studs 38 threaded downthrough platform 3t) and extending down within a fraction of an inch ofmember 34. These may be spaced at intervals and in the number needed tosuit the size and confi uration of the particular panel.

The pressure differential across membrane 34,- is created by a greatersubstantial negative pressure in plenum chamber as, i.e. on the innerface of panel 34, and a less-er negative pressure on the lower articlecontacting surface of panel 34-. This can be achieved by providingsomewhat restricted gas flow passages e.g. 4t? and 42 in patterns ofselected configuration and location in the member. When a negativepressure is initially applied to chamber 35, a negative pressure is alsocreated beneath panel 34 because of flow through orifices, but since theupper surface area of the panel iscntirely instantly exposed to agreater negative pressure, a pressure differential is formed.

These orifices can be plural in number as shown, or singular. Theorifice means may be only at the center of the platen if desired, aswill be understood, or can extend somewhat from the center as shown. Itis necessary to limit the outward extent of the orifices to an areasmaller than that of the smallest surface area or pattern area to behoisted.

The negative pressure in plenum chamber 35 is created by evacuationmeans 14 which may comprise a conventional centrifugal blower. It may bemounted directly on platform for example. Its central axial inlet 59(FIG. 4) communicates with plenum chamber as by a central opening 52 inplatform 3%. It is rotationally driven at high speeds by electricalmotor. 16 which may also be mounted above the blower and supportedforexample by suitable bracing means 60 The tangential exhaust outlet 54of the blower is con trolled by a pivotal butterfly valve'24 on pivotshaft es. This valve may be shifted between its closed and openpositions manually or by power means. If the latter, a sprocket 7t canbe attached to shaft 66. The sprocket is rotated at alternativedirections with a length of roller 4 chain 72 with one end attached to acore 74 of a solenoid 22 and the other end attached to a tension coilreturn spring 73 attached to bracing member St! or the like.

A plurality of upstanding rigid columns 84 are mounted to the platform,and have suitable hoist connection means such as eyelets 86 forattachment of tension members such as the plurality of chains 88 forhoisting the assembly on a suitable crane or the like (not shown).

Method The operation of the mechanism may be controlled remotely, by theoperator holding a hand held switching control unit 18- connectedelectrically by extensible electrical cord 19 to electrical controlsystem 20 associated in conventional fashion with motor 16, and withsolenoid 212.

To lift a pattern of cartons, e.g. cartons C1, C2, C3 and ton pattern ispositioned within the general confines of' a membrane 34, valve 24 isopened by shifting solenoid core 74 with electrical actuation throughthe control assembly 38. This instantly creates a substantial negativepressure in plenum chamber 35 by exhaustion of the air therein throughport 52 and inlet 50 to the centrifugal blower. As this negativepressure forms, air is also drawn up through passages 46 and 42, butsince the flow through these ports is somewhat restricted, the negativepressure above the panel is initially substantially greater than belowthe panel, causing a pressure differential across member 34. Thispressure differential causes the panel to flex or bow inwardly againstthe stops, so as to have a concave undersurface. Although the flexingaction is initially caused by a pressure differential across the panel,this differential subsequentlyis largely reduced to an insignificantamount because the air in the space above the cartons is substantiallyevacuated, particularly since a substantially complete seal is formedbetween the outer carton pattern periphery and the panel. The flexedcurvature is maintained by the upward thrust of the carton due toatmospheric pressure pressing on the bottom of the cartons and imposinga load up on member 34 which conforms with pattern size. p

This flexing action is very significant. Extensive experimentation showsthat the flexing action occurs in a manner to cause the compoundcurvature of the panel to match the actual pattern configuration, sothat the peripheral edge of the carton pattern remains in closeengagement with the member. This causes a nearly complete sealingcontact between the upper outer edge of the outermost cartons as shownin FIG. 5, while the entire membrane area inside the periphery flexesaway from the cartons to form a space. By sealing is meant that any airflow occurring between the cartons and the panel is such a smallfraction of the blower drawing capacity that it is insignificant. (Inactualuse, it hasbeen found that the undersurface of the flexible panelmay even have small spaced embossments protruding a A or so withoutsignificantly hindering the action.)

This pattern conforming flexing action occurs automatically, andrepeatedly, even though the pattern varies considerably in size andconfiguration. For example, the same unit works just as effectively,without modification, on a 30 x 307 pattern, or a 48" x 53" pattern.

With the formation of the concave under surface of' member 34, thecontinuous space $9 formed over the entire surface area to be hoisted(except at the'outermost peripheral edge of the outermost cartons)creates excellent evacuation communication of the entire surface area toexhausting ports 40 and 42, causing a pressure differential over theheight of the cartons. When the hoist mechanism is elevated to lift thecartons off their support surface, the cartons retain their horizontallyaligned relation as shown in FIG. 5, held tightly as a group, so thatthe inner cartons do not even contact the flexed member. The cartons canbe dislodged only with considerable force, as has been proven. Ofcourse, the particular amount of lifting force employed will depend uponthe weight, size and nature of the articles. This can be varied inconventional fashion by varying the size of the hoist membrane, thecapacity of the evacuating means, and the like. It has been found thatcartons weighing several hundred pounds can be readily hoisted withsafety and reliability using an evacuation means capacity typical ofpresent blowers.

As noted previously, the flexing action which occurs with evacuation ishighly desirable, as Well as the resulting compound curvature of theconcave flexed membrane, to obtain automatic adaptation to diferingdimensions and configurations. In some instances, however, it ispossible to employ a permanently flexed membrane. Lifting action withsuch a permanently curved membrane can be achieved on pre-selectedconfigurations, for example, of square patterns utilizing a squarelifting membrane, or round patterns using a square lifting membrane.However, the permanently flexed membrane will not automaticallyaccommodate different configurations, e.g. a square membrane on anelongated, rectangular pattern. Although sealing will readily occuralong the two short edges of such a carton pattern, the elongated edgeswill allow leakage unless the lifting platen is correspondingly shaped.This permanently curved unit can therefore be considered as part of thebroadest aspects of the novel concept, but does not constitute thepreferred form of the invention.

It is also conceivable that the structure can employ a flexible membraneother than a semi-rigid, non-stretch able metallic panel like that shownin FIGS. 4 and 5, but any stretchable membrane must be controlled overits extent to prevent significant stretching, and is not as universal inthe pattern configuration to be accommodated since its final curvaturetends to be determined by the means used to limit its flexing andstretching. Specifically, referring to the modified form of theapparatus in FIG. 6, the assembly 110 includes a blower subassembly 14and motor (not shown) cooperative with platform 130 as in FIG. 1. Theplat-form may have a depending peripheral portion defining a plenumchamber 135 having its bottom surface closed by a flexible membrane 134.In this instance, the membrane comprises an element such as rubber. Itincludes orifices 140 and 142 through it. If the member is stretchable,i.e. rubber Without integral reinforcing to prevent its stretchingaction, a negative pressure in plenum chamber 135 could causeuncontrolled deformation of the membrane into the housing. Therefore, apermanently conflgurated open mesh control member such as a bowed,inwardly concavely curved rigid screen or expanded metal layer 159 orthe like is extended across the opening on the bottom of the insideplenum chamber 135, adjacent member 134. This control element determinesthe flexing extent, to eflfectively prevent significant stretching ofthe orificed membrane 134. If the membrane 134 is formed of a reinforcedrubber or plastic, e.g. having a non-stretchable sheet or sheets as ofmetal screen, woven fabrics or the like bonded or otherwise secured toit, so as to no longer have significant stretch characteristics, thenthe membrane 134 can be nicely employed in the manner of the first formof the invention.

The operation of this modified form is basically like that describedwith respect to FIGS. 4 and 5. Specifically, the hoist is lowered untilthe carton pattern contacts the generally fiat membrane 134, at whichtime the exhaust valve of the blower is opened to cause evacuation ofplenum chamber to form a negative pressure in it. This creates apressure differential across membrane 134 due to the restricted air flowup through the membrane, flexing the membrane up against the form orstop means 159 in a predetermined concavely curved configuration. Theperiphery of the carton pattern remains in sealing engagement withmember 134 so that a shallow space is created over the entire cartonpattern area except at the peripheral edge. A pressure differential isthereby created over the cartons since the spacing above the cartons issubjected to a negative pressure by flow of the air through this shallowspace and ports and 142.

This form of the invention is not preferred, since membrane 134 willtend to repeatedly deform to the specific configuration of member 159,rather than flexing in a pattern to match the peripheral edge of thecartons or other like articles to be hoisted. Therefore, it would workeffectively for predetermined patterns, e.g., if the hoist membrane issquare, it will hoist a square or a round pattern. However, an oblongpattern would tend to create leakage along the elongated edges of thepattern, with this leakage being detrimental in some instances,depending upon the weight of the cartons or like articles to be hoisted.Therefore, the preferred form of the invention illustrated in FIGS. 4and 5 have advantages over this construction. It is entirelyconceivable, however, that this modified construction could be employedin some instances.

Certain additional details of construction of the apparatus couldconceivably be changed within the concept presented herein. Hence, it isintended that the invention is to be limited only by the scope of theappended claims and the reasonable equivalent methods and structures tothose defined therein.

I claim:

1. A pressure differential hoist comprising: support means includingmeans for attachment of elevating means; a lifting platen on one side ofsaid support means and secured on its periphery to said support means;said platen having first and second opposite faces; means forming aplenum chamber adjacent to and communicant with the first face of saidplaten, between it and said support means; said second face comprisingan article contacting surface for engaging the surface area of articlesto be hoisted; evacuation means operatively associated with said plenumchamber to form a negative pressure therein and on said platen firstface; restricted port means from said plenum chamber to said secondsurface to allow formation of an article hoisting negative pressureadjacent said second surface slightly less than said plenum chambernegative pressure to cause a pressure differential across said platen;and said platen being non-stretchable, semi-rigid, and slightly flexiblewithin its periphery to bodily flex a slight amount into a compoundcurvature toward said support under the pressure differential appliedthereto, causing said first face to be convex and said second face to beconcave, to create an air evacuation space adjacent said second face andthe surface area of articles to be hoisted, and to form a peripheraledge seal between said second face and the periphery of said surfacearea.

2. A pressure differential hoist for hoisting articles having a surfacearea, comprising: hoisting housing means forming an internal plenumchamber and having bottom panel means having an article contacting outersurface; said panel means being generally non-stretchable, and slightlyflexible to bend into a compound curvature of large radius with saidouter surface concave, under the influence of a negative pressure insaid plenum chamber, to create a shallow space at said second surfaceand cause a peripheral edge seal to the article surface area; evacuatingmeans operatively associated with said plenum chamber to create anegative pressure therein, and passage means from said plenum chamber tosaid outer surface to create a negative pressure at said outer surface,said shallow space, and the article surface area, to create a pressuredifferential across the articles.

3. A pressure differential hoist comprising: hoistable housing meansforming an internal plenum chamber having a bottom, article-contacting,orificed surface means, said surface means having a slight compoundconcave curvature, at least when said plenum chamber is at a negativepressure; and evacuation means operatively associated with said plenumchamber to create a negative pressure therein and create a negativepressure at said surface means for lifting articles contacting it.

4. The hoist in claim 2 wherein said panel means is a thin membranehaving orifice means in the central portions thereof.

5. The hoist in claim 2 wherein said panel means is a relatively thinmetal plate having a plurality of restricted orifices in a pattern.

6. The hoist in claim 2 including stop means in said housing limitingthe flexing of said panel means.

7. The hoist in claim 3 wherein said surface means includes a porouscurved form and a flexible, stretchable membrane shiftable from arelaxed condition away from said form, to a flexed condition againstsaid form under a pressure difierential applied thereto.

8. A method of providing a slightly flexible lifting panel havinglimited air flow orifices therethrough hoisting one or more articleshaving a generally fiat surface area comprising the steps of: placingone face of said orificed lifting panel against said surface area,creating a negative pressure at the second face of said panel, andthrough the orifices in said panel creating a smaller negative pressureat said surface area, thereby also simultaneously creating a pressuredifferential across said panel to flex said panel in a concavity awayfrom said surface area to cause a slight compound curvature of saidpanel at said second surface, to create a space between said panel andsubstantially all of said surface area, while retaining a peripheralseal between said second surface of said flexed panel and said surfacearea; and lifting said panel and articles.

References Cited UNETED STATES PATENTS 949,850 2/1910 Smith 294-641,025,692 5/1912 Farley 294-64 1,225,724 5/1917 Smith 294-64 2,311,5252/1943 Ebbs 294-64 X 2,920,989 1/1960 Cochran et al 294-64 X HUGO O.SCHULZ, Primary Examiner.

